Continents can grow by accumulating crustal material along their edges at convergent boundaries. Here, a terrane carried by a subducting plate is fused to the edge of a continent. The attachment of terranes such as this contributed to continental growth along the west coast of North America.
As an oceanic plate descends to hotter depths beneath the overriding plate, it is heated and releases water. The presence of hot, water-rich liquids causes the overlying rock to begin melting. The resulting magma is less dense than the surrounding rock, so it rises up toward the surface where it collects in magma chambers. Volcanic eruptions happen when magma from these chambers reaches the surface. Over millions of years, repeated eruptions build volcanic mountains on the overriding plate.
Rift zones are divergent plate boundaries. Most of them occur along the seafloor as mid-ocean ridges. Where two plates are moving away from each other, molten rock rises to the surface, cools, and solidifies. Generally, each eruption of lava splits the rocks formed in the previous eruption, so the youngest rocks are always at the rift.
Videos, Tutorials and Websites
Plate Boundaries AnimationPlates and Boundaries
Plate Tectonics - Boundaries and Motion
Plate Tectonics
Boundaries Explanations
Plate Tectonics - Interactive Map
Continental Drift Animation
Video Lesson on Plate Tectonics - Click On the Picture Below
1) Begins with close-up showing mid-ocean ridge topography with magma chamber below, 2) magma rises and new ocean plate spreads away from ridge.
Observe animations of processes that occur along plate boundaries.
Observe an Animation Showing Growth of a Continent
Continents can grow by accumulating crustal material along their edges at convergent boundaries. Here, a terrane carried by a subducting plate is fused to the edge of a continent. The attachment of terranes such as this contributed to continental growth along the west coast of North America.Observe an Animation of Volcanoes at a Subduction Zone
As an oceanic plate descends to hotter depths beneath the overriding plate, it is heated and releases water. The presence of hot, water-rich liquids causes the overlying rock to begin melting. The resulting magma is less dense than the surrounding rock, so it rises up toward the surface where it collects in magma chambers. Volcanic eruptions happen when magma from these chambers reaches the surface. Over millions of years, repeated eruptions build volcanic mountains on the overriding plate.
Observe an Animation of Volcanoes Along a Rift Zone
Rift zones are divergent plate boundaries. Most of them occur along the seafloor as mid-ocean ridges. Where two plates are moving away from each other, molten rock rises to the surface, cools, and solidifies. Generally, each eruption of lava splits the rocks formed in the previous eruption, so the youngest rocks are always at the rift.=
Games and Practice
Plate Tectonics MatchingRags to Riches
Plate Tectonics Practice Quiz
Game - Place the Boundaries
Plate Tectonics Game Show
Things From Class
Plate Tectonics Vocabulary